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// <copyright file="MockSimpleModbusTCP.cs" company="Microsoft Corporation">
// The MIT License (MIT)
// 
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namespace Test.Robotics.Hardware.Modbus
{
    using System;
    using Microsoft.Robotics.Hardware.Modbus;
    using Microsoft.VisualStudio.TestTools.UnitTesting;

    /// <summary>
    /// Mock for a simple ModbusTCP connection;
    /// </summary>
    public class MockSimpleModbusTCPConnection : ISimpleModbusTCPConnection 
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="MockSimpleModbusTCPConnection"/> class.
        /// </summary>
        public MockSimpleModbusTCPConnection()
        {
            this.ExpectedRegisterValues = null;
            this.RegisterValuesToReturn = null;
        }

        /// <summary>
        /// Gets or sets the expected register values for PresetMultipleRegisters
        /// </summary>
        public ushort[] ExpectedRegisterValues { get; set; }

        /// <summary>
        /// Gets or sets the register values to return for ReadInputRegisters
        /// </summary>
        public ushort[] RegisterValuesToReturn { get; set; }

        /// <summary>
        /// Implement the IDisposable interface
        /// </summary>
        public void Dispose()
        {
            this.Dispose(true);
            GC.SuppressFinalize(this);
        }

        /// <summary>
        /// Set multiple registers.  Asserts that the registers to be set are equal to <c>ExpectedRegisterValues</c> if it is non-null
        /// </summary>
        /// <param name="unitID">Slave device ID.</param>
        /// <param name="addressOfFirstRegister">Address of register to begin writing at.</param>
        /// <param name="wordsToWriteCount">Number of words to write.</param>
        /// <param name="registers">Values to write.</param>
        public void PresetMultipleRegisters(byte unitID, ushort addressOfFirstRegister, ushort wordsToWriteCount, ushort[] registers)
        {
            if (this.ExpectedRegisterValues != null)
            {
                Assert.AreEqual(this.ExpectedRegisterValues.Length, wordsToWriteCount, "Attemp to write incorrect number of registers");

                for (int i = 0; i < wordsToWriteCount; ++i)
                {
                    Assert.AreEqual(this.ExpectedRegisterValues[i], registers[i], "Register " + i + " did not have the expected value");
                }
            }
        }

        /// <summary>
        /// Creates a ReadInputRegisters request, sends it to the slave device, 
        /// reads the response, and places them into the out parameter. 
        /// </summary>
        /// <param name="unitID">ID of the slave device.</param>
        /// <param name="addressOfFirstRegister">Address of the first register to read.</param>
        /// <param name="wordsToReadCount">Number of 16-bit words to read.</param>
        /// <param name="registers">Returns the desired number of registers with each register being assigned a value 
        /// equal to it's index.</param>
        public void ReadInputRegisters(byte unitID, ushort addressOfFirstRegister, ushort wordsToReadCount, out ushort[] registers)
        {
            registers = new ushort[wordsToReadCount];

            // If RegisterValuesToReturn hasn't been set, just set each register value equal to its index.
            if (this.RegisterValuesToReturn == null)
            {
                for (ushort i = 0; i < wordsToReadCount; ++i)
                {
                    registers[i] = i;
                }
            }
            else
            {
                if (this.RegisterValuesToReturn.Length < wordsToReadCount)
                {
                    throw new ArgumentException("wordsToReadCount exceeds RegisterValuesToReturn.Length");
                }

                Array.Copy(this.RegisterValuesToReturn, registers, wordsToReadCount);
            }
        }

        /// <summary>
        /// Dispose of resources -- nothing to do
        /// </summary>
        /// <param name="disposing">Indicates whether or not Dispose() was called.</param>
        protected virtual void Dispose(bool disposing)
        {
        }
    }
}
